When it comes to huge carnivores, there were no larger land animals than all the giant theropods we grew up with, and here is a list of my top 10 largest theropods.
#10 Edmarka rex/Torvosaurus:
One of the largest north american theropods, the largest specimen (CPS 1002) known from a scapula, is estimated at 11 m long, and probably upwards 3000-4000 kg
#9 Suchomimus tenerensis:
The largest specimen of this african spinosaurid (MNHN GDF 500) is estimated to measure 11.65 m (by Scott Hartman) and over 3816-4700 kg, some even claimed a weight of 5,200 kg was possible, the skull is 1.4 m long, and has over 90 non serrated,cone shaped teeth.
#8 Sauroniops pachytholus:
Known from a fragmentary skull bone of similar size to the equivalent in Acrocanthosaurus, this animal might have measured over 11.3 m long and if was similar to Acrocanthosaurus, it may have weighted 5,690 kg.
#7 Allosaurus fragillis/amplexus:
If we talk about large carnosaurs, no animal had such exceptional size variation as Allosaurus.
The estimates of size of this north american theropod vary, while most specimens seem to reach 8-10 m in length and 1,800-3,500 kg, like AMNH 600, AMNH 666, DINO 2560, AMNH 680 and NMMNH P-26083, some fragmentary specimens seem to reach exceptionally larger sizes such as AMNH 5767, whose size, estimated by a 327 mm coracoid bone was estimated as of 11.9 m and a weight of 5,700 kg, it may not even be an A. fragillis after all
#6 Acrocanthosaurus atokensis:
The largest specimen (NCSM 1435) is estimated as of 11.5 m in length and perhaps upwards 6,100 kg in weight, it consists in a partial skeleton about 57% complete and has a skull measuring 1.29 m in premaxilla-q length, it stands over 3 meters tall and has very powerful yet short forelimbs, its size was enormous, making it the third largest north american theropod.
#5 Saurophaganax maximus:
The largest specimen (OMNH 1935) consists in a humerus 480-540 mm long, scaling by the specimens MOR 693, USNM 4734, and UUVP 6000, the obtained sizes are 11.25-12.7 m, 11.45-13 m and 10.0-11.2 m using the two figures with the three specimens respectively, and the mass would be anywhere between 4,995 and 7,811 kg, is this is true then S. maximus would be the second largest north american theropod.
#4 Carcharodontosaurus saharicus:
Coming from measurements of both holotype (IPHG 1927) and Neotype (SMG DIN-1) I estimated a length of 12.7 m, even Scott Hartman stated that a size about a feet longer than the type of Giganotosaurus is plausible, if this is true, an animal weighting slightly more than 7,000 kg is reasonable, this would make it the largest african carnosaur and the second largest theropod known from Africa.
The largest and only skull (SMG din-1) measures 1.55 m in pmx-Qj, which seems to indicate that this animal was of comparable size to Giganotosaurus, specially because Giganotosaurus has a 1.54 m long skull.
#3 Giganotosaurus carolinii:
Discovered in Argentina, this animal is one of the largest theropod dinosaurs ever discovered and the largest of Argentina and South America. The type specimen (MUCPv-CH1) is estimated to reach 12.4 m, and estimated to weight 6,800-7,000 kg (Hartman stated it could have fluctuated from 6,400 to 7,200 kg over the years.) A second specimen (MUCPv-95) is estimated to measure 6.5% more, if this is true this animal would measure 13.2 m and weight 8,200 kg.
#2 Tyrannosaurus rex:
The largest coelurosaur and the largest north american theropod. It is the most well known large theropod of all times and the most recognizable.
Discovered in 1857, in Montana, this enormous predator (the most fearsome looking one) is known from just over 50 skeletons, The holotype (CMN 9380) measures 11.9 m and weights 6,800 kg, while, the largest specimen (FMNH PR 2081) is estimated as of 12-12.5 m (with a mean of 12.3 m) and about 8,400 kg in weight, making it a heavyweight champion in the world of theropods, not only more robust than every large theropod, but just heavier than the extremely long paratype of Giganotosaurus, however, the rest of the specimens come just under that.
measuring by femur size, I estimated that the average specimen may have been about 11.5 m long, but just comes as speculation, a mean size of 11-12 m is perfectly fit in.
#1 Spinosaurus aegyptiacus.
If the speculations and estimated sizes are correct, Spinosaurus should be the largest carnivore dinosaur ever.
The estimations suggest sizes about 13.2-15.6 m in length and just over 6,700-11,000 kg in weight, this animal would be the ultimate heavyweight theropod of all times and the largest african theropod, the skull is estimated to be 1.64-1.75 m long, if the estimates are true, the skull should be the longest of all skulls of meat eating dinosaurs known, T.rex and Giganotosaurus had 1.52/1.54 m skulls respectively.